Internal combustion engine with port communication

ABSTRACT

A method of feeding air to an internal combustion engine having at least first and second internal cavities, including: completing the intake phase of the first combustion chamber of the first internal cavity by feeding compressed air into the first combustion chamber until a maximum volume thereof is reached; during a beginning of the compression phase of the first combustion chamber and a simultaneous beginning of the intake phase of the second combustion chamber of the second internal cavity, feeding compressed air from the first combustion chamber into the second combustion chamber; closing a communication between the first and second combustion chambers and completing the intake phase of the second combustion chamber by feeding compressed air into the second combustion chamber until a maximum volume thereof is reached.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/799,965 filed Mar. 13, 2013, the entire contents of which areincorporated by reference herein.

TECHNICAL FIELD

The application relates generally to internal combustion engines and,more particularly, to such engines operating under the principle of theMiller cycle.

BACKGROUND OF THE ART

Internal combustion engines operating under the principle of the Millercycle usually have an open inlet port during the beginning of thecompression phase of the combustion chamber(s). In a reciprocatingengine, the Miller cycle may be obtained through timing of the openingof the inlet valve. In a rotary engine such as a Wankel engine, theMiller cycle may be obtained through proper positioning of the inletport. The Miller cycle engine usually has a volumetric compression ratiolower than its volumetric expansion ratio.

Typically, the Miller cycle engine is used with a turbocharger toprevent loss of air during the beginning of the compression phase and toincrease the pressure compression ratio. However, during the beginningof the compression phase when the inlet port is open, compression mustbe typically performed against the pressure of the turbocharger, whichusually creates pressure losses.

SUMMARY

In one aspect, there is provided an internal combustion enginecomprising: at least two rotatable bodies; an outer body defining arespective internal cavity for each of the bodies, each of the bodiesbeing sealingly and rotationally received within the respective internalcavity to each define at least one combustion chamber of variable volumeundergoing a cycle defining successive phases of intake, compression,combustion and exhaust; at least one inlet port for each respectiveinternal cavity, the at least one inlet port being in fluidcommunication with each of the at least one combustion chamber of therespective internal cavity at least during the intake phase thereof anda beginning portion of the compression phase thereof; at least oneexhaust port for each respective internal cavity, the at least oneexhaust port being in fluid communication with each of the at least onecombustion chamber of the respective internal cavity during the exhaustphase thereof; a rotatable shaft, the bodies being drivingly engaged tothe shaft in an angularly offset manner with the beginning portion ofthe compression phase of the at least one combustion chamber defined byeach of the bodies being simultaneous with at least a beginning of theintake phase of the at least one combustion chamber defined by adifferent one of the bodies; a plenum for receiving pressurized air; anda respective conduit providing a fluid communication between the atleast one inlet port of the respective internal cavity of each of thebodies and the at least one inlet port of the respective internal cavityof the different one of the bodies, each respective conduit being influid communication with the plenum.

In another aspect, there is provided an engine comprising: aturbocharger having a compressor; a rotary internal combustion enginehaving: at least two rotors, an outer body defining: a respectiveinternal cavity for each of the rotors, each of the rotors beingsealingly and rotationally received within the respective internalcavity to define a plurality of combustion chambers of variable volumeeach undergoing a cycle defining successive phases of intake,compression, combustion and exhaust, a primary inlet port for eachrespective internal cavity, the primary inlet port being in fluidcommunication with each of the at least one combustion chamber of therespective internal cavity during the intake phase thereof and abeginning portion of the compression phase thereof; a secondary inletport for each respective internal cavity, the secondary inlet port beingin fluid communication with each of the at least one combustion chamberof the respective internal cavity during a secondary portion of thecycle thereof extending at most over a beginning of the intake phase andan end of the exhaust phase, and an exhaust port for each respectiveinternal cavity, the exhaust port being in fluid communication with eachof the combustion chambers of the respective internal cavity during theexhaust phase thereof; a rotatable shaft, the rotors being drivinglyengaged to the shaft in an angularly offset manner with the beginningportion of the compression phase of the at least one combustion chamberdefined by each of the rotors being simultaneous with at least part ofthe secondary portion of the cycle of the combustion chambers defined bya different one of the rotors; a plenum in fluid communication with thecompressor; and a respective conduit providing a fluid communicationbetween the primary inlet port of the respective internal cavity of eachof the rotors and the secondary inlet port of the respective internalcavity of the different one of the rotors, each respective conduit beingin fluid communication with the plenum.

In a further aspect, there is provided a method of feeding air to aninternal combustion engine having at least first and second internalcavities each sealingly and rotationally receiving a respective rotortherewithin, each of the internal cavities having a primary inlet portand a secondary inlet port in fluid communication therewith, the methodcomprising: feeding compressed air to a combustion chamber of the firstcavity through the primary inlet port thereof while increasing a volumeof the combustion chamber until a maximum volume thereof is reached;while reducing a volume of the combustion chamber from the maximumvolume and at least in part while increasing a volume of a combustionchamber of the second cavity, feeding compressed air from the combustionchamber of the first cavity through the primary inlet port thereof intothe combustion chamber of the second cavity through the secondary inletport thereof; closing a communication between the primary inlet port andthe combustion chamber of the first cavity and further reducing thevolume of the combustion chamber of the first cavity until a minimumvolume thereof is reached; and feeding compressed air to the combustionchamber of the second cavity through the primary inlet port thereofwhile increasing the volume of the combustion chamber of the secondcavity until a maximum volume thereof is reached.

In a further aspect, there is provided a method of feeding air to aninternal combustion engine having at least first and second internalcavities, the first internal cavity defining at least a first combustionchamber, the second internal cavity defining at least a secondcombustion chamber, the first and second combustion chambers each havinga variable volume and undergoing a cycle defining successive phases ofintake, compression, combustion and exhaust, the method comprising:completing the intake phase of the first combustion chamber by feedingcompressed air into the first combustion chamber until a maximum volumethereof is reached; during a beginning of the compression phase of thefirst combustion chamber and a simultaneous beginning of the intakephase of the second combustion chamber, feeding compressed air from thefirst combustion chamber into the second combustion chamber; closing acommunication between the first and second combustion chambers andcompleting the intake phase of the second combustion chamber by feedingcompressed air into the second combustion chamber until a maximum volumethereof is reached.

In further aspect, there is provided a method of feeding air to aninternal combustion engine having at least first and second internalcavities, the first internal cavity defining at least a first combustionchamber with variable volume, the second internal cavity defining atleast a second combustion chamber with variable volume, the methodcomprising: feeding compressed air to the first combustion chamber whileincreasing a volume of the first combustion chamber until a maximumvolume thereof is reached; while reducing a volume of the firstcombustion chamber from the maximum volume and while increasing a volumeof the second combustion chamber, feeding compressed air from the firstcombustion chamber into the second combustion chamber; closing acommunication between the first and second combustion chambers andfurther reducing the volume of the first combustion chamber until aminimum volume thereof is reached; and with the communication betweenthe first and second combustion chambers closed, feeding compressed airto the second combustion chamber while further increasing the volumethereof until a maximum volume thereof is reached.

In a further aspect, there is provided an internal combustion enginecomprising: an outer body defining internal cavities each slidinglyreceiving a respective one of a plurality of pistons to define arespective combustion chamber of variable volume undergoing a cycledefining successive phases of intake, compression, combustion andexhaust; at least one inlet port for each of the internal cavities andin fluid communication with the respective combustion chamber at leastduring the intake phase thereof and a beginning portion of thecompression phase thereof; at least one exhaust port for each of theinternal cavities and in fluid communication with the respectivecombustion chamber of the respective internal cavity during the exhaustphase thereof; a rotatable shaft, the pistons being drivingly engaged tothe shaft in an angularly offset manner; a plenum for receivingpressurized air; and a plurality of conduits in fluid communication withthe plenum, each of the plurality of conduits defining a fluidcommunication between a first respective one of the internal cavities asecond respective one of the internal cavities through the at least oneinlet port of the first and second respective one of the internalcavities; wherein the pistons are angularly offset such that for each ofthe plurality of conduits, the combustion chamber of the firstrespective one of the internal cavities undergoes the beginning portionof the compression phase simultaneously with the combustion chamber ofthe second respective one of the internal cavities undergoing thebeginning portion of the intake phase.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures in which:

FIG. 1 is a schematic view of an engine in accordance with a particularembodiment;

FIG. 2 is a schematic cross-sectional view of a rotary internalcombustion engine in accordance with a particular embodiment, which canbe used in an engine such as shown in FIG. 1;

FIG. 3 is a schematic view of connections between the cavities of arotary engine such as shown in FIG. 2, in accordance with a particularembodiment;

FIG. 4 is a schematic cross-sectional view of a conduit of FIG. 3, inaccordance with a particular embodiment; and

FIG. 5 is a schematic view of connections between the cavities of areciprocating internal combustion engine which can be used in an enginesuch as shown in FIG. 1, in accordance with a particular embodiment.

DETAILED DESCRIPTION

Referring now to FIG. 1, an engine 8 is schematically shown. The engine8 includes an internal combustion engine 10, 110 generally including aplurality of moveable bodies each received in a corresponding internalcavity of an outer body to each define at least one combustion chamber.For example, the internal combustion engine 10, 110 may be areciprocating engine with a plurality of internal cavities eachreceiving a moveable body in the form of a reciprocating piston. Theinternal combustion engine 10, 110 may alternately be a rotary enginewith a plurality of internal cavities each receiving a moveable body onthe form of a rotatable body or rotor. The moveable bodies drive acommon load. In the embodiment shown, the common load includes an outputshaft 16 which may be for example connected to a propeller through areduction gearbox (not shown) and to which the moveable bodies of theinternal combustion engine 10, 110 are engaged.

The engine 8 also includes a turbocharger 17, which in the embodimentshown include a compressor 19 and a turbine 22 which are drivinglyinterconnected by a shaft 23. The compressor 19 and the turbine 22 mayeach be a single-stage device or a multiple-stage device with a singleshaft or split on multiple independent shafts in parallel or in series,and may be a centrifugal or axial device. In the embodiment shown, theshaft 23 of the turbocharger 17 rotates independently of the commonload. The compressor 19 of the turbocharger 17 compresses the air beforeit enters the internal combustion engine 10, 110.

In a particular embodiment, the engine 8 is a compound cycle engine suchas described for example in Lents et al.'s U.S. Pat. No. 7,753,036issued Jul. 13, 2010, as described in Julien et al.'s U.S. Pat. No.7,775,044 issued Aug. 17, 2010, or as described in U.S. patentapplication Ser. Nos. 13/554,517 and 13/554,564 both filed Jul. 20,2012, the entire contents of all of which are incorporated by referenceherein. For example, the exhaust flow is supplied to a power turbine 25also driving the common load. The power turbine 25 is connected to theoutput shaft 16 through an appropriate type of transmission 27, forexample a planetary, star, offset or angular gear system. The outlet ofthe power turbine 25 is in fluid communication with an inlet of theturbocharger turbine 22. Energy is extracted from the exhaust gasexiting the power turbine 25 by the turbocharger turbine 22 to drive thecompressor 19 via the connecting shaft 24.

In another embodiment, the internal combustion engine 10, 110 is notcompounded and the power turbine 25 is omitted. For example, the engine8 may include only the internal combustion engine 10 and a turbocharger17. The internal combustion engine 10, 110 operates under the principleof the Miller cycle, as will be further detailed below.

Referring to FIG. 2, in a particular embodiment, the internal combustionengine 10 is a rotary engine. Although FIG. 2 shows a Wankel engine, itis understood that the rotary engine 10 may alternately have a differentconfiguration than that of a Wankel engine. For example, in a particularembodiment, the rotary engine may be a single or eccentric type rotaryengine in which the rotor rotates about a fixed center of rotation. Forexample, the rotary engine may be a sliding vane engine, such asdescribed in U.S. Pat. No. 5,524,587 issued Jun. 11, 1996 or in U.S.Pat. No. 5,522,356 issued Jun. 4, 1996, the entire contents of both ofwhich are incorporated by reference herein. In another particularembodiment, the rotary engine may be an oscillatory rotating engine,including two or more rotors rotating at different angular velocities,causing the distance between portions of the rotors to vary and as suchthe chamber volume to change. In another particular embodiment, therotary engine may be a planetary rotating engine having a differentgeometry than that of the Wankel engine, such as for example a planetaryengine having an internal cavity with an epitrochoid profile definingthree lobes and a rotor with four apex portions. Examples of suchnon-Wankel rotary engines are shown in Applicant's U.S. application Ser.No. 13/750,523 filed Jan. 25, 2013, the entire contents of which isincorporated by reference herein. Other rotary engine geometries arealso possible.

Still referring to FIG. 2, in the particular embodiment shown, therotary engine 10 comprises an outer body 12 having a plurality of rotorcavities 20 (only one of which is shown) each defined by axially-spacedend walls 14 and a peripheral wall 18 extending therebetween, with arotor 24 received in each cavity 20. The inner surface of the peripheralwall 18 of each cavity 20 has a profile defining two lobes, which ispreferably an epitrochoid.

The outer body 12 may be integral, containing all the rotor cavities 20,or alternately be defined by a plurality of body portions (separate fromone another or interconnected), for example each defining a respectiveone of the cavities 20 and receiving a respective one of the rotors 24.

Each rotor 24 is received within the respective cavity 20, with thegeometrical axis of the rotor 24 being offset from and parallel to theaxis of the outer body 12. Each rotor 24 has axially spaced end faces 26adjacent to the outer body end walls 14, and a peripheral face 28extending therebetween. The peripheral face 28 defines threecircumferentially-spaced apex portions 30 and a generally triangularprofile with outwardly arched sides. The apex portions 30 are in sealingengagement with the inner surface of peripheral wall 18 to form threerotating working or combustion chambers 32 between the inner rotor 24and outer body 12. A recess (not shown) is defined in the peripheralface 28 of the rotor 24 between each pair of adjacent apex portions 30,to form part of the corresponding chamber 32.

The combustion chambers 32 are sealed. Each rotor apex portion 30 has anapex seal 52 extending from one end face 26 to the other and protrudingradially from the peripheral face 28. Each apex seal 52 is biasedradially outwardly against the peripheral wall 18 through a respectivespring. An end seal 54 engages each end of each apex seal 52, and isbiased against the respective end wall 14 through a suitable spring.Each end face 26 of the rotor 24 has at least one arc-shaped face seal60 running from each apex portion 30 to each adjacent apex portion 30,adjacent to but inwardly of the rotor periphery throughout its length. Aspring urges each face seal 60 axially outwardly so that the face seal60 projects axially away from the adjacent rotor end face 26 intosealing engagement with the adjacent end wall 14 of the cavity. Eachface seal 60 is in sealing engagement with the end seal 54 adjacent eachend thereof.

Although not shown, each rotor 24 is journaled on an eccentric portionof a shaft and includes a phasing gear co-axial with the rotor axis,which is meshed with a fixed stator phasing gear secured to the outerbody co-axially with the shaft. The shaft rotates each rotor 24 and themeshed gears guide the rotor 24 to perform orbital revolutions withinthe respective internal cavity 20. The shaft rotates three times foreach complete rotation of one rotor 24 as it moves around the respectiveinternal cavity 20. Oil seals are provided around the phasing gear toprevent leakage flow of lubricating oil radially outwardly thereofbetween the respective rotor end face 26 and outer body end wall 14.

During each rotation of the rotor 24, each chamber 32 varies in volumesand moves around the internal cavity 20 to undergo cycles with eachcycle including the four phases of intake, compression, expansion andexhaust, these phases being similar to the strokes in areciprocating-type internal combustion engine having a four-strokecycle.

For each cavity 20, a primary inlet port 40 is defined through one ofthe walls of the stator body 12 for admitting air in turn into each ofthe combustion chambers 32. In the embodiment shown, the primary inletport 40 is a peripheral port defined as an opening through theperipheral wall 18. In another embodiment, the primary inlet port 40 mayhave a different configuration, for example be defined through one ofthe end walls 14, with another primary inlet port being optionallydefined in the other one of the end walls 14. The primary inlet port 40is in fluid communication with the turbocharger compressor 19 (see FIG.1), as will be further detailed below. The primary inlet port 40 is influid communication with each combustion chamber 32 during the intakephase thereof and a beginning of the compression phase thereof. As such,the rotary engine 10 operates under the principle of the Miller cycle,with its volumetric compression ratio lower than its volumetricexpansion ratio, and with the primary inlet port 40 remaining open, i.e.in communication with the chamber 32, during the beginning of thecompression phase.

For each cavity 20, an exhaust port 44 is defined through one of thewalls of the stator body 12 for discharge of the exhaust gases from thecombustion chambers 32. In the embodiment shown, the exhaust port 44 isa peripheral port defined as an opening through the peripheral wall 18.In another embodiment, the exhaust port 44 may have a differentconfiguration, for example be defined through one of the end walls 14,with another exhaust port being optionally defined in the other one ofthe end walls 14.

For each cavity 20, a secondary inlet port or purge port 42 is alsodefined through one of the walls of the stator body 12 for admitting airin turn into each of the combustion chambers 32. The secondary inletport 42 is located rearwardly of the primary inlet port 40 and forwardlyof the exhaust port 44 relative to the direction R of the rotorrevolution and rotation. In the embodiment shown, the secondary inletport 42 is a peripheral port defined as an opening through theperipheral wall 18. In another embodiment, the secondary inlet port 42may have a different configuration, for example be defined through oneof the end walls 14, with another secondary inlet port being optionallydefined in the other one of the end walls 14. The secondary inlet port42 is also in fluid communication with the turbocharger compressor 19(see FIG. 1), as will be further detailed below. The secondary inletport 42 is in fluid communication with each combustion chamber 32 duringa portion of its cycle; this portion may include a beginning of theintake phase and/or an end of the exhaust phase.

In the present specification including the claims, “intake phase” isintended to refer to the portion of the cycle during which the chamber32 is in communication with at least one inlet port 40, 42 and duringwhich the volume of the chamber 32 increases such as to draw airtherein, while “compression phase” is intended to refer to the portionof the cycle between the intake phase and the ignition phase duringwhich the volume of the chamber 32 decreases, starting at the point inthe cycle where the maximum chamber volume is reached after intake,regardless if actual air compression occurs. For example, in aparticular embodiment, compression may be inexistent or minimal duringthe beginning of the compression phase when the primary inlet port 40 isopen.

In use, through each rotation of the rotor 24, each chamber 32 is filledwith compressed air through the primary inlet port 40 and the secondaryinlet port 42 during its intake phase as its volume increases. The airis then further compressed as by reducing the volume of the rotatingchamber 32, with the beginning of the compression phase being performedwith the primary inlet port 40 still open, i.e. in communication withthe chamber 32, the primary inlet port 40 closing during the compressionphase. Once the air is further compressed, near minimum volume of thechamber 32, the ignition phase occurs: the air is mixed with fuel from afuel source 9 (see FIG. 1) and the resulting air-fuel mixture isignited. In a particular embodiment, the fuel is heavy fuel e.g. diesel,kerosene (jet fuel), equivalent biofuel, etc. Alternately, the fuel maybe any other adequate type of fuel suitable for injection as described,including non-heavy fuel such as for example gasoline or liquid hydrogenfuel. The fuel is delivered such that the chamber 32 is stratified witha rich fuel-air mixture near the ignition source and a leaner mixtureelsewhere, thus providing a so-called stratified charge arrangement, andthe fuel-air mixture may be ignited within the housing using anysuitable ignition system known in the art. The rotary engine 10 mayinclude a pilot subchamber (not shown) receiving the ignition system anda pilot injector injecting a portion of the fuel therein for ignition.

After ignition, the combustion gases expand and force the volume of thechamber 32 to increase. The combustion or exhaust gases exit the chamber32 through the exhaust port 44 during the exhaust phase. At the end ofthe exhaust phase, the chamber 32 may communicate with both thesecondary inlet port 42 and the exhaust port 44, and the air enteringthe chamber 32 through the secondary inlet port 42 may be used to purgeremaining exhaust gases from the chamber 32.

Referring to FIG. 3, a connection arrangement between the differentcavities of the rotary engine 10 is shown. In the embodiment shown, therotary engine 10 includes two rotor cavities 20 a,b, each receiving arespective rotor 24 (not shown in FIG. 3) and each having a primaryinlet port 40 a,b and a secondary inlet port 42 a,b in communicationwith the combustion chambers defined therein.

A first conduit 62 provides for fluid communication between the primaryinlet port 40 a of the first cavity 20 a and the secondary inlet port 42b of the second cavity 20 b. A second conduit 64 provides for fluidcommunication between the primary inlet port 40 b of the second cavity20 b and the secondary inlet port 42 a of the first cavity 20 a. Aplenum 21 receives the compressed air from the turbocharger compressor19, and the first and second conduits 62, 64 are also in fluidcommunication with the plenum 21.

The rotors are engaged to the shaft in an angularly offset manner. Eachcombustion chamber defined in the first cavity 20 a undergoes thebeginning of its compression phase (i.e. the part of the compressionphase where the primary inlet port 40 a communicates with the chamber)while a corresponding combustion chamber defined in the second cavity 20b undergoes at least part of the portion of its cycle in communicationwith its secondary inlet port 42 b, which in a particular embodiment isat the beginning of its intake phase. As such, the first conduit 62allows for the compressed air overflowing from the primary inlet port 40a of the first cavity 20 a during the beginning of its compression phaseto be fed into the secondary inlet port 42 b of the second cavity 20 b,in a particular embodiment together with air from the plenum 21.

Similarly, each combustion chamber defined in the second cavity 20 bundergoes the beginning of its compression phase (i.e. the part of thecompression phase where the primary inlet port 40 b communicates withthe chamber) while a corresponding combustion chamber defined in thefirst cavity 20 a undergoes at least part of the portion of its cycle incommunication with its secondary inlet port 42 a, which in a particularembodiment is at the beginning of its intake phase. As such, the secondconduit 64 allows for the compressed air overflowing from the primaryinlet port 40 b of the second cavity 20 b during the beginning of itscompression phase to be fed into the secondary inlet port 42 a of thefirst cavity 20 a, in a particular embodiment together with air from theplenum 21.

In a rotary engine including more than two rotors, the rotor cavitiesmay be connected in pairs, i.e. with the first and second conduitsinterconnecting the same rotor cavities, or connected with differentrotor cavities, i.e. with the primary inlet port of a first rotor beingconnected to the secondary inlet port of a second rotor and thesecondary inlet port of the first rotor being connected to the primaryinlet port of a third rotor, based on the relative timing (angularoffset) of the rotors.

Referring to FIG. 4, a particular embodiment for the first conduit 62 isshown, with the second conduit 64 being identical or similar thereto.The conduit 62 is configured such as to form a Venturi to assist in thecirculation of compressed air from the primary inlet port 40 a of thefirst cavity 20 a to the secondary inlet port 42 b of the second cavity20 b. In a particular embodiment, the conduit 62 has a circularcross-section. The conduit includes a first segment 86 extending fromthe plenum 21. A second segment 88 extends from the first segment 86,and receives the connection with the primary inlet port 40 a of thefirst cavity 20 a. A third segment 90 extends from the second segment 88and a fourth segment 92 extends from the third segment 90, with thethird segment providing for a gradual transition between the differentdimensions of the second and fourth segments 88, 92. The fourth segment92 receives the fluid communication with the secondary inlet port 42 bof the second cavity 20 b.

It can be seen that the second segment 88 has a diameter D2 which issmaller than the diameter D1 of the first segment 86, and smaller thanthe diameter D3 of the fourth segment 92. In a particular embodiment,the ratio D1/D2 and the ratio D1/D3 are between 1 and 2. In anotherparticular embodiment, the ratio D1/D2 and the ratio D1/D3 are fromabout 1.5 to about 1.8. Other values are also possible.

The third segment 90 is tapered to define a progressive transitionbetween the different diameters D2 and D3 of the second and fourthsegments 88, 92. The outer wall of the third segment 90 extends at anangle α from the outer wall of the fourth segment 92. In a particularembodiment, the angle α is from about 2.5° to about 7.5°. In anotherparticular embodiment, the angle α is from about 3° to about 4°. Othervalues are also possible.

In the embodiment shown, the fluid communication between the primaryinlet port 40 a and the second segment 88 is provided through a conduitportion 94 extending at an angle θ with respect to a perpendicular to acentral axis C of the second segment 88. In a particular embodiment, theangle θ is from about −45° to about 60°. In another particularembodiment, the angle θ is from about 30° to about 60°. Other values arealso possible.

In use, the compressed air is fed into the combustion chambers 32 of therotary engine 10 in accordance with the following. The compressed airfrom the plenum 21 is fed through the first conduit 62 and into acombustion chamber of the first cavity 20 a through its primary inletport 40 a as the chamber undergoes the intake phase, i.e. as its volumeis increasing. Compressed air is also fed to the chamber through thesecond conduit 64 through its secondary inlet port 40 a during thebeginning of the intake phase, and optionally the end of the exhaustphase.

After the intake phase, when the maximum volume of the chamber isreached, the compression phase begins and the volume of the chamber ofthe first cavity 20 a is reduced, at first while its primary inlet port40 a remains open. The air overflows out of the first cavity 20 athrough the open primary inlet port 40 a and into the first conduit 62,where it is fed to a combustion chamber of the second cavity 20 bthrough its secondary inlet port 42 b, with the chamber of the secondcavity 20 b being at the end of its exhaust phase or at the beginning ofits intake phase. The chamber of the second cavity 20 b undergoes thebeginning of its intake phase, with its volume increasing, while the airfrom the first cavity 20 a is received through its secondary inlet port42 b. Depending on the relative pressures, air may also be fed from theplenum 21 to the second cavity 20 b through the first conduit 62 andsecondary inlet port 42 b. The communication between the combustionchamber of the first cavity 20 a and its primary inlet port 40 a is thenclosed, and the air within the combustion chamber of the first cavity 20a is further compressed during the remainder of the compression phase asthe volume of the chamber is reduced to its minimum value.

The intake phase of the chamber of the second cavity 20 b continues, andcompressed air is fed from the plenum 21 through the second conduit 64and into the combustion chamber of the second cavity 20 b through itsprimary inlet port 40 b. After the intake phase, when the maximum volumeof the chamber is reached, the compression phase begins and the volumeof the chamber of the second cavity 20 b reduces, at first while itsprimary inlet port 40 b remains open. The air overflows out of thesecond cavity 20 b through the open primary inlet port 40 b and into thesecond conduit 64, where it is fed to another combustion chamber of thefirst cavity 20 a through its secondary inlet port 42 a, this chamber ofthe first cavity 20 a being at the end of its exhaust phase or at thebeginning of its intake phase. This other chamber of the first cavity 20a undergoes the beginning of its intake phase, with its volumeincreasing, while the air from the second cavity 20 b is receivedthrough its secondary inlet port 42 a. Depending on the relativepressures, air may also be fed from the plenum 21 to the first cavity 20a through the second conduit 64 and secondary inlet port 42 a. Thecommunication between the chamber of the second cavity 20 b and itsprimary inlet port 40 b is then closed, and the air within thecombustion chamber of the second cavity 20 b is further compressed untilthe end of its compression phase as the volume of the chamber is reducedto its minimum value.

Referring to FIG. 5, a similar connection arrangement between thedifferent cavities of a reciprocating engine 110 is shown. In theembodiment shown, the reciprocating engine 110 includes four cavities120 a,b,c,d each receiving a respective piston 124 a,b,c,d to eachdefine a single combustion chamber, and each having a respective inletport 140 a,b,c,d′ and a respective exhaust port 144 a,b,c,d incommunication with the combustion chamber. A respective valveselectively allows and prevents the fluid communication between theinlet ports 140 a,b,c,d and the respective cavity 120 a,b,c,d andbetween the exhaust ports 144 a,b,c,d and the respective cavity 120a,b,c,d.

A plenum 121 receives the compressed air from the turbochargercompressor 19. First, second, third and fourth conduits 162, 164, 166,168 are defined by different sections of interconnected passages whichselectively communicate with each other through one-way valves.

The pistons 124 a,b,c,d are engaged to the shaft in an angularly offsetmanner with each cavity 120 a,b,c,d undergoing the beginning of itscompression phase with its inlet port open while another cavityundergoes part or all of its intake phase with its inlet port also open.In the embodiment shown, the pistons fire in the following order: firstpiston 124 a, second piston 124 b, fourth piston 124 d and third piston124 c.

As such, in the embodiment shown, first, second, third and fourth inletpassages 170 a,b,c,d extend from a respective one of the inlet ports 140a,b,c,d to the plenum 121. A first transverse passage 172 interconnectsthe first, second and fourth inlet passages 170 a,b,d, while a secondtransverse passage 174 interconnects the first, third and fourth inletpassages 170 a,c,d. A first one-way valve 176 a allows a flow in thefirst transverse passage 172 from the first inlet passage 170 a to thesecond inlet passage 170 b while preventing the flow in the oppositedirection. A second one-way valve 176 b allows a flow in the firsttransverse passage 172 from the second inlet passage 170 b to the fourthinlet passage 170 d while preventing the flow in the opposite direction.A third one-way valve 176 c allows a flow in the second transversepassage 174 from the fourth inlet passage 170 d to the third inletpassage 170 c while preventing the flow in the opposite direction. Afourth one-way valve 176 d allows a flow in the second transversepassage 174 from the third inlet passage 170 c to the first inletpassage 170 a while preventing the flow in the opposite direction.

Thus, in the embodiment shown, when the first cavity 120 a is at thebeginning of its compression phase with the valve of its inlet port 140a remaining open, the second cavity 120 b is in its intake phase, withthe valve of its inlet port 140 b also being open. A first conduit 162provides for fluid communication between the first inlet port 140 a andthe second inlet port 140 b, as defined by the first inlet passage 170a, the portion of the first transverse passage 172 extending between thefirst and second inlet passages 170 a,b including the first one-wayvalve 176 a, and the second inlet passage 170 b. The valves of the thirdand fourth inlet ports 140 c,d are closed and prevent communication ofthe first conduit 162 with the third and fourth cavities 120 c,d.

The second cavity 120 b then begins its compression phase with the valveof the second inlet port 140 b remaining open, and the fourth cavity 120d is in its intake phase, with the valve of the fourth inlet port 140 dalso being open. A second conduit 164 provides for fluid communicationbetween the second inlet port 140 b and the fourth inlet port 140 d,defined by the second inlet passage 170 b, the portion of the firsttransverse passage 172 extending between the second and fourth inletpassages 170 b,d including the second one-way valve 176 b, and thefourth inlet passage 176 d. The valves of the first and third inletports 140 a,c are closed and prevent communication of the second conduit164 with the first and third cavities 120 a,c.

The fourth cavity 120 d then begins its compression phase with the valveof the fourth inlet port 140 d remaining open, and the third cavity 120c is in the intake phase, with the valve of the third inlet port 140 calso being open. A third conduit 166 provides for fluid communicationbetween the fourth inlet port 140 d and the third inlet port 140 c,defined by the fourth inlet passage 170 d, the portion of the secondtransverse passage 174 extending between the fourth and third inletpassages 170 d,c including the third one-way valve 176 c, and the thirdinlet passage 170 c. The valves of the first and second inlet ports 140a,b are closed and prevent communication of the third conduit 166 withthe first and second cavities 120 a,b.

The third cavity 120 c then begins its compression phase with the valveof the third inlet port 140 c remaining open, and the first cavity 120 ais in the intake phase, with the valve of the first inlet port 140 aalso being open. A fourth conduit 168 provides for fluid communicationbetween the third inlet port 140 c and the first inlet port 140 a,defined by the third inlet passage 170 c, the portion of the secondtransverse passage 174 extending between the third and first inletpassages 170 c,a including the fourth one-way valve 176 d, and the firstinlet passage 170 a. The valves of the second and fourth inlet ports 140b,d are closed and prevent communication of the fourth conduit 168 withthe second and fourth cavities 120 b,d.

The conduits 162, 164, 166, 168 are also in communication with theplenum 121 through the inlet passages 170 a,b,c,d. In a particularembodiment, the conduits 162, 164, 166, 168 have a Venturi shape asdescribed above.

In an alternate embodiment, the internal combustion engine 10, 110 is arotary engine with a single inlet port for each cavity, and acommunication similar to that described above for the reciprocatingengine 110 is provided. An another embodiment, the internal combustionengine 10, 110 is a reciprocating engine with a primary and a secondaryinlet port for each cavity, and a communication similar to thatdescribed above for the rotary engine 10 is provided.

In a particular embodiment, the conduits 62, 64, 162, 164, 166, 168which allow circulation of the air expelled from each cavity 20 a,b, 120a,b,c,d at the beginning of the compression phase of each chamber into achamber of another cavity 20 a,b, 120 a,b,c,d simultaneously undergoingits intake phase allow for a reduction of the pressure losses which mayotherwise be associated with the use of the Miller cycle in an internalcombustion engine.

In a particular embodiment, the internal combustion engine 10,110 is apremix engine where the fuel is for example gasoline, and the fuel maybe injected in the inlet port; in this case, the air circulated betweenthe inlet ports may also include fuel mixed therewith.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without departing from the scope of the invention(s)disclosed. Modifications which fall within the scope of the presentinvention will be apparent to those skilled in the art, in light of areview of this disclosure, and such modifications are intended to fallwithin the appended claims.

The invention claimed is:
 1. A method of feeding air to an internalcombustion engine having at least first and second internal cavities,the first internal cavity defining at least a first combustion chamber,the second internal cavity defining at least a second combustionchamber, the first and second combustion chambers each having a variablevolume and undergoing a cycle defining successive phases of intake,compression, combustion and exhaust, the method comprising: completingthe intake phase of the first combustion chamber by feeding compressedair into the first combustion chamber until a maximum volume thereof isreached; during a beginning of the compression phase of the firstcombustion chamber and a simultaneous beginning of the intake phase ofthe second combustion chamber, feeding compressed air from the firstcombustion chamber into the second combustion chamber; closing acommunication between the first and second combustion chambers andcompleting the intake phase of the second combustion chamber by feedingcompressed air into the second combustion chamber until a maximum volumethereof is reached.
 2. The method as defined in claim 1, wherein thefirst and second internal cavities each sealingly and rotationallyreceive a respective rotor therewithin.
 3. The method as defined inclaim 1, wherein the beginning of the compression phase of the firstcombustion chamber is simultaneous with the end of the exhaust phase andthe beginning of the intake phase of the second combustion chamber, andcompressed air is also fed from the first combustion chamber into thesecond combustion chamber during the end of the exhaust phase of thesecond combustion chamber.
 4. The method as defined in claim 1, wherein:feeding the compressed air from the first combustion chamber into thesecond combustion chamber includes feeding the compressed air from thefirst combustion chamber through a primary inlet port of the firstinternal cavity and into the second combustion chamber through asecondary inlet port of the second internal cavity; and completing theintake phase of the second combustion chamber with the communicationbetween the first and second combustion chambers closed includes feedingthe compressed air to the second combustion chamber through a primaryinlet port of the second internal cavity.
 5. The method as defined inclaim 1, wherein the internal combustion engine further includes a thirdinternal cavity defining at least a third combustion chamber withvariable volume and undergoing a cycle defining successive phases ofintake, compression, combustion and exhaust, the method furthercomprising: during a beginning of the compression phase of the secondcombustion chamber and a simultaneous beginning of the intake phase ofthe third combustion chamber, feeding compressed air from the secondcombustion chamber into the third combustion chamber; closing acommunication between the second and third combustion chambers andcompleting the intake phase of the third combustion chamber by feedingcompressed air into the third combustion chamber until a maximum volumethereof is reached.
 6. The method as defined in claim 5, wherein theinternal combustion engine further includes a fourth internal cavitydefining at least a fourth combustion chamber with variable volume andundergoing a cycle defining successive phases of intake, compression,the method further comprising: during a beginning of the compressionphase of the third combustion chamber and a simultaneous beginning ofthe intake phase of the fourth combustion chamber, feeding compressedair from the third combustion chamber into the fourth combustionchamber; closing a communication between the third and fourth combustionchambers and completing the intake phase of the fourth combustionchamber by feeding compressed air into the fourth combustion chamberuntil a maximum volume thereof is reached; during a beginning of thecompression phase of the fourth combustion chamber and a simultaneousbeginning of the intake phase of the first combustion chamber, feedingcompressed air from the fourth combustion chamber into the firstcombustion chamber; and closing a communication between the fourth andfirst combustion chambers before completing the intake phase of thefirst combustion chamber by feeding compressed air into the firstcombustion chamber until the maximum volume thereof is reached.
 7. Themethod as defined in claim 1, wherein the first internal cavity definesat least a first additional combustion chamber with variable volume andundergoing a cycle defining successive phases of intake, compression,combustion and exhaust, the method further comprising: during abeginning of the compression phase of the second combustion chamber anda simultaneous beginning of the intake phase of the first additionalcombustion chamber, feeding compressed air from the second combustionchamber into the first additional combustion chamber; closing acommunication between the second combustion chamber and the firstadditional combustion chamber, and completing the intake phase of thefirst additional combustion chamber by feeding compressed air into thefirst additional combustion chamber until a maximum volume thereof isreached.
 8. The method as defined in claim 7, wherein the secondinternal cavity defines at least a second additional combustion chamberwith variable volume and undergoing a cycle defining successive phasesof intake, compression, combustion and exhaust, the method furthercomprising: during a beginning of the compression phase of the firstadditional combustion chamber and a simultaneous beginning of the intakephase of the second additional combustion chamber, feeding compressedair from the first additional combustion chamber into the secondadditional combustion chamber; closing a communication between the firstand second additional combustion chambers and completing the intakephase of the second additional combustion chamber by feeding compressedair into the second additional combustion chamber until a maximum volumethereof is reached; during a beginning of the compression phase of thesecond additional combustion chamber and a simultaneous beginning of theintake phase of the first combustion chamber, feeding compressed airfrom the second additional combustion chamber into the first combustionchamber; and closing a communication between the second additionalcombustion chamber and the first combustion chamber before completingthe intake phase of the first combustion chamber by feeding compressedair into the first combustion chamber until the maximum volume thereofis reached.
 9. The method as defined in claim 8, wherein: feedingcompressed air from the second additional combustion chamber into thefirst combustion chamber includes feeding the compressed air from thesecond additional combustion chamber through a primary inlet port of thesecond internal cavity and into the first combustion chamber through asecondary inlet port of the first internal cavity; feeding compressedair to the first combustion chamber with the communication between thesecond additional combustion chamber and the first combustion chamberclosed includes feeding the compressed air to the first combustionchamber through a primary inlet port of the first internal cavity;feeding compressed air from the first combustion chamber into the secondcombustion chamber includes feeding the compressed air from the firstcombustion chamber through the primary inlet port of the first internalcavity and into the second combustion chamber through a secondary inletport of the second internal cavity; feeding compressed air to the secondcombustion chamber with the communication between the first and secondcombustion chambers closed includes feeding the compressed air to thesecond combustion chamber through the primary inlet port of the secondinternal cavity; feeding compressed air from the second combustionchamber cavity into the first additional combustion chamber includesfeeding the compressed air from the second combustion chamber throughthe primary inlet port of the second internal cavity and into the firstadditional combustion chamber through the secondary inlet port of thefirst internal cavity; feeding compressed air to the first additionalcombustion chamber with the communication between the second combustionchamber and the first additional combustion chamber closed includesfeeding the compressed air to the first additional combustion chamberthrough the primary inlet port of the first internal cavity; feedingcompressed air from the first additional combustion chamber into thesecond additional combustion chamber includes feeding the compressed airfrom the first additional combustion chamber through the primary inletport of the first internal cavity and into the second additionalcombustion chamber through the secondary inlet port of the secondinternal cavity; and feeding compressed air to the second additionalcombustion chamber with the communication between the first and secondadditional combustion chambers closed includes feeding the compressedair to the second additional combustion chamber through the primaryinlet port of the second internal cavity.
 10. A method of feeding air toan internal combustion engine having at least first and second internalcavities, the first internal cavity defining at least a first combustionchamber with variable volume, the second internal cavity defining atleast a second combustion chamber with variable volume, the methodcomprising: feeding compressed air to the first combustion chamber whileincreasing a volume of the first combustion chamber until a maximumvolume thereof is reached; while reducing a volume of the firstcombustion chamber from the maximum volume and while increasing a volumeof the second combustion chamber, feeding compressed air from the firstcombustion chamber into the second combustion chamber; closing acommunication between the first and second combustion chambers andfurther reducing the volume of the first combustion chamber until aminimum volume thereof is reached; and with the communication betweenthe first and second combustion chambers closed, feeding compressed airto the second combustion chamber while further increasing the volumethereof until a maximum volume thereof is reached.
 11. The method asdefined in claim 10, wherein the first and second internal cavities eachsealingly and rotationally receive a respective rotor therewithin. 12.The method as defined in claim 10, wherein: feeding the compressed airfrom the first combustion chamber into the second combustion chamberincludes feeding the compressed air from the first combustion chamberthrough a primary inlet port of the first internal cavity and into thesecond combustion chamber through a secondary inlet port of the secondinternal cavity; and feeding the compressed air to the second combustionchamber with the communication between the first and second combustionchambers closed includes feeding the compressed air to the secondcombustion chamber through a primary inlet port of the second internalcavity.
 13. The method as defined in claim 10, wherein the internalcombustion engine further includes a third internal cavity defining atleast a third combustion chamber with variable volume, the methodfurther comprising: while reducing the volume of the second combustionchamber from the maximum volume thereof and while increasing a volume ofthe third combustion chamber, feeding compressed air from the secondcombustion chamber into the third combustion chamber; closing acommunication between the second and third combustion chambers andfurther reducing the volume of the second combustion chamber until aminimum volume thereof is reached; and with the communication betweenthe second and third combustion chambers closed, feeding compressed airto the third combustion chamber while further increasing the volumethereof until a maximum volume thereof is reached.
 14. The method asdefined in claim 13, wherein the internal combustion engine furtherincludes a fourth internal cavity defining at least a fourth combustionchamber with variable volume, the method further comprising: whilereducing the volume of the third combustion chamber from the maximumvolume thereof and while increasing a volume of the fourth combustionchamber, feeding compressed air from the third combustion chamber intothe fourth combustion chamber; closing a communication between the thirdand fourth combustion chambers and further reducing the volume of thethird combustion chamber until a minimum volume thereof is reached; withthe communication between the third and fourth combustion chambersclosed, feeding compressed air to the fourth combustion chamber whilefurther increasing the volume thereof until a maximum volume thereof isreached; and while reducing the volume of the fourth combustion chamberfrom the maximum volume thereof and while increasing a volume of thefirst combustion chamber, feeding compressed air from the fourthcombustion chamber into the first combustion chamber.
 15. The method asdefined in claim 10, wherein the first internal cavity defines at leasta first additional combustion chamber with variable volume, the methodfurther comprising: while reducing the volume of the second combustionchamber from the maximum volume thereof and while increasing a volume ofthe first additional combustion chamber, feeding compressed air from thesecond combustion chamber into the first additional combustion chamber;closing a communication between the second combustion chamber and thefirst additional combustion chamber, and further reducing the volume ofthe second combustion chamber until a minimum volume thereof is reached;and with the communication between the second combustion chamber and thefirst additional combustion chamber closed, feeding compressed air tothe first additional combustion chamber while increasing the volume ofthe first additional combustion chamber until a maximum volume thereofis reached.
 16. The method as defined in claim 15, wherein the secondinternal cavity defines at least a second additional combustion chamberwith variable volume, the method further comprising: while reducing thevolume of the first additional combustion chamber from the maximumvolume thereof and while increasing a volume of the second additionalcombustion chamber, feeding compressed air from the first additionalcombustion chamber into the second additional combustion chamber;closing a communication between the first and second additionalcombustion chambers, and further reducing the volume of the firstadditional combustion chamber until a minimum volume thereof is reached;and with the communication between the first and second additionalcombustion chambers closed, feeding compressed air to the secondadditional combustion chamber while increasing the volume of the secondadditional combustion chamber until a maximum volume thereof is reached;wherein feeding the compressed air to the first combustion chamber whileincreasing the volume of the first combustion chamber until the maximumvolume thereof is reached includes: feeding compressed air from thesecond additional combustion chamber into the first combustion chamberwhile reducing the volume of the second additional combustion chamber offrom the maximum volume thereof and while increasing the volume of thefirst combustion chamber, closing the communication between the secondadditional combustion chamber and the first combustion chamber, and withthe communication between the second additional combustion chamber andthe first combustion chamber closed, feeding compressed air to the firstcombustion chamber while further increasing the volume thereof until themaximum volume thereof is reached.
 17. The method as defined in claim16, wherein: feeding compressed air from the second additionalcombustion chamber into the first combustion chamber includes feedingthe compressed air from the second additional combustion chamber througha primary inlet port of the second internal cavity and into the firstcombustion chamber through a secondary inlet port of the first internalcavity; feeding compressed air to the first combustion chamber with thecommunication between the second additional combustion chamber and thefirst combustion chamber closed includes feeding the compressed air tothe first combustion chamber through a primary inlet port of the firstinternal cavity; feeding compressed air from the first combustionchamber into the second combustion chamber includes feeding thecompressed air from the first combustion chamber through the primaryinlet port of the first internal cavity and into the second combustionchamber through a secondary inlet port of the second internal cavity;feeding compressed air to the second combustion chamber with thecommunication between the first and second combustion chambers closedincludes feeding the compressed air to the second combustion chamberthrough the primary inlet port of the second internal cavity; feedingcompressed air from the second combustion chamber into the firstadditional combustion chamber includes feeding the compressed air fromthe second combustion chamber through the primary inlet port of thesecond internal cavity and into the first additional combustion chamberthrough the secondary inlet port of the first internal cavity; feedingcompressed air to the first additional combustion chamber with thecommunication between the second combustion chamber and the firstadditional combustion chamber closed includes feeding the compressed airto the first additional combustion chamber through the primary inletport of the first internal cavity; feeding compressed air from the firstadditional combustion chamber into the second additional combustionchamber includes feeding the compressed air from the first additionalcombustion chamber through the primary inlet port of the first internalcavity and into the second additional combustion chamber through thesecondary inlet port of the second internal cavity; and feedingcompressed air to the second additional combustion chamber with thecommunication between the first and second additional combustionchambers closed includes feeding the compressed air to the secondadditional combustion chamber through the primary inlet port of thesecond internal cavity.